<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            padding: 0;
            margin: 0;
        }
        .div1{
            height: 200px;
            width: 200px;
            background-color: red;
            margin: 20px;
        }
        .div2{
            height: 200px;
            width: 200px;
            background-color: green;
            margin: 20px;
        }

        .div3{
            height: 400px;
            width: 400px;
            background-color: blue;
            /* margin: 20px; */
            /* overflow: hidden; */
            float: left;
        }
        .div4{
            height: 200px;
            width: 200px;
            background-color: violet;
            margin: 20px;
            /* float: left; */
        }
    </style>
</head>
<body>
    <div class="div1"></div>
    <div class="div2"></div>

    <div class="div3">
        <div class="div4"></div>
    </div>
</body>
</html>